An important problem in multi-radio multi-channel wireless mesh networks is how to perform efficient network-wide broadcasting. While route discovery or energy efficiency is the major concern for broadcasting in mobile ad-hoc networks or sensor networks, in WMNs, more attention should be paid to the high-throughput schemes. In this paper, we propose an interference-aware broadcast routing and channel assignment scheme for IEEE802.11-based multi-radio multi-channel mesh networks. We first formulate the problem as a mixed integer linear programming which jointly consider the broadcast routing and channel assignment. And then we propose heuristic suboptimal algorithms. Our schemes enable nodes to operate with minimum interference while the channel diversity can be fully exploited. Simulation results show that out schemes can significantly improve the broadcast performance compared with previous work.